[sdiy] I've got one word for you: Plastics

[Richard Kirk Moore (rkmoore)]

The plastic that I was complaining about before has cured harder than I thought at first.  While not perfect, I think the resulting keys will work nicely for my organ.  I haven't messed with trying to dye the plastic to the proper beige, but that's not a major concern for me.  For anyone curious, I took a few pictures of the process that can be seen here:

https://umdrive.memphis.edu/rkmoore/sdiy/keymoldmosaicsmall.jpg

Thanks to everyone for the information!

-Richard


________________________________________
From: kheck73 at aol.com [kheck73 at aol.com]
Sent: Thursday, January 28, 2010 9:38 PM
To: Richard Kirk Moore (rkmoore); synth-diy at dropmix.xs4all.nl
Subject: Re: [sdiy] I've got one word for you: Plastics

I've worked in materials testing labs where mounting compounds are used to prepare samples for sectioning and analysis. One family of compounds are cold curing plastics, epoxy, polyurethane, and acrylic. The mixture is usually of a liquid and a powder. The two big companies that make the supplies are Struers (struers.com) and Buehler (buehler.com). Look under "cold mount consumables". I worked mostly with the epoxies, and they set really hard. I believe we coated the molds with some sort of release compound like a talcum powder, but its been a while ago and my memory is fuzzy. It cures clear or with a yellowish hue to it. I see Struers has color dyes you can add to some of the epoxies and acrylics, but I don't see white or black. You might be able to cast the key, roughen the surface a bit with fine grit paper, then give it a shot of gloss paint, but I don't know how well it would stick.

-Karl.
-----Original Message-----
From: Richard Kirk Moore (rkmoore) <rkmoore at memphis.edu>
To: synth-diy at dropmix.xs4all.nl <synth-diy at dropmix.xs4all.nl>
Sent: Thu, Jan 28, 2010 8:27 pm
Subject: [sdiy] I've got one word for you: Plastics


Hi everyone,

It's been a long time since I've posted anything.  My current project is getting
my Hammond H-111 organ fully operational.  It's in strikingly good condition,
but several of the 50-year-old plastic keys have broken.  Instead of buying
someone else's 50-year-old keys pulled from a donor organ, I am trying to cast
new ones.  Using a Smooth-On OOMOO 30 silicone rubber and Smooth-Cast 300
urethane plastic I have made a mold and cast a key.  The resulting key is good
and mounts in place nicely, but the new plastic is not quite as rigid as the
original one.  As an EE, materials science is pretty far outside of my working
knowledge.  Does anyone know of a better plastic that I could use at home for
key casting?

Thanks,
Richard

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